In general, a check valve is mounted on a fuel tank of an automobile or the like, the check valve being arranged to make a fuel vapor flow outside to prevent the fuel tank from bursting when the pressure in the fuel tank rises to a predetermined value or more while making the outside air flow in from the outside of the fuel tank to prevent the fuel tank from being crushed when the pressure in the fuel tank falls to a predetermined value or less with respect to outside air pressure.
JP-UM-S56-131067-B discloses a two-direction valve that includes two valves arranged to open in directions different from each other in a casing having two opening ports while at least one of the valves is made from resin, and a valve portion made from rubber is fixed to the valve via a thin metallic plate.
The valve portion can be made from rubber, includes an annular shape, and a step is provided to the outer rim of the valve portion. The valve is arranged to open when the pressure in the fuel tank rises. The valve has a circular shape, and includes a cylindrical wall standing from the outer rim of the upper end portion and a protrusion protruding from the cylindrical wall in the radial inner direction. The thin metallic plate has an annular shape, and the rim thereof is bent to have the approximate shape of the letter “L”. When the step of the valve portion is pressed from above, the inner rim of the thin metallic plate and the outer rim of the thin metallic plate is engaged with the lower surface of the protrusion of the valve, and the valve portion is fixed to the valve via the thin metallic plate.
The two-direction valve has the configuration such that the valve portion is fixed to the valve via the thin metallic plate as described above. However, assembly work such as inserting the thin metallic plate into the cylindrical wall of the valve to make the outer rim of the thin metallic plate sink be under and engaged with the lower surface of the protrusion of the valve is required. Further, assembly work such as inserting the valve portion into the inner rim of the thin metallic plate to press the step of the valve portion with the inner rim of the thin metallic plate may be also required. Thus, the two-direction valve may not be efficiently assembled with its complicated structure.